1. Field of the Invention
Rotary rock bits and earth boring cutters used in well drilling, mining and the like commonly operate submerged in liquid which is circulated to remove heat and cuttings from the work site. A dynamic seal isolates this circulating, abrasive-laden liquid from the lubricated bearing surfaces which support the rotating rock cutting cones. A pressure balancing system minimizes pressure differentials across the seal.
2. Description of the Prior Art
Face seals and shaft seals comprised of an O-ring confined between relatively rotating surfaces within a groove of rectangular cross section and exerting a predetermined amount of deformative squeeze against the O-ring are well known in the prior art. A relatively small amount of squeeze is desirable to minimize heating, wear and frictional losses. Some pressure differentials are known to occur across the seal and enough squeeze to resist such pressures must be used. "Twisting", "bunching" and "snaking" conditions also interfere with the sealing functions of such O-ring seals. U.S. Pat. No. 2,200,151 teaches use of an O-ring confined in a groove of cross sectional shape similar to that herein described. The seal is characterized as a static face seal wherein squeeze is varied by using pressure across the seal to move housing surfaces normal to the sealing direction.
The instant invention is distinguished over this cited art in that it is a dynamic shaft seal wherein the squeeze is varied by using pressure across the seal to move the O-ring parallel to the sealing direction.